DropdownDataGrid how to preselect something?

I'm using a DropdownDataGrid and I cannot seem to define the preselected value.
This component has 7 fields that are related to this:

Data: here I'm passing the data object
TextProperty: Here I'm selecting from the dropdown the property of my DataObject I want to show
ValueProperty: Here I'm selecting from the dropdown the property of my DataObject I want to use as value
Value: not sure what this is for
SelectedValue: not sure what this is for
DefaultValue: not sure what this is for

I tried filling these fields, I can manage to have the correct value preselected when the dropdown is CLOSED (so I already see it selected the right value), but
what I cannot achieve is, when you open the dropdown, the correct value WON'T be highlighted!!

But if I click on that row, my change event won't trigger, because that means that value is the selected one, but it's not highlighted